chrome/common/metrics/metrics_log_base.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/common/metrics/metrics_log_base.h"
   6
   7 #include "base/base64.h"
   8 #include "base/basictypes.h"
   9 #include "base/md5.h"
  10 #include "base/metrics/histogram_base.h"
  11 #include "base/metrics/histogram_samples.h"
  12 #include "base/sys_byteorder.h"
  13 #include "base/sys_info.h"
  14 #include "chrome/common/chrome_version_info.h"
  15 #include "chrome/common/logging_chrome.h"
  16 #include "chrome/common/metrics/proto/histogram_event.pb.h"
  17 #include "chrome/common/metrics/proto/system_profile.pb.h"
  18 #include "chrome/common/metrics/proto/user_action_event.pb.h"
  19
  20 using base::Histogram;
  21 using base::HistogramBase;
  22 using base::HistogramSamples;
  23 using base::SampleCountIterator;
  24 using base::Time;
  25 using base::TimeDelta;
  26 using metrics::HistogramEventProto;
  27 using metrics::SystemProfileProto;
  28 using metrics::UserActionEventProto;
  29
  30 namespace {
  31
  32 // Any id less than 16 bytes is considered to be a testing id.
  33 bool IsTestingID(const std::string& id) {
  34   return id.size() < 16;
  35 }
  36
  37 // Converts the 8-byte prefix of an MD5 hash into a uint64 value.
  38 inline uint64 HashToUInt64(const std::string& hash) {
  39   uint64 value;
  40   DCHECK_GE(hash.size(), sizeof(value));
  41   memcpy(&value, hash.data(), sizeof(value));
  42   return base::HostToNet64(value);
  43 }
  44
  45 SystemProfileProto::Channel AsProtobufChannel(
  46     chrome::VersionInfo::Channel channel) {
  47   switch (channel) {
  48     case chrome::VersionInfo::CHANNEL_UNKNOWN:
  49       return SystemProfileProto::CHANNEL_UNKNOWN;
  50     case chrome::VersionInfo::CHANNEL_CANARY:
  51       return SystemProfileProto::CHANNEL_CANARY;
  52     case chrome::VersionInfo::CHANNEL_DEV:
  53       return SystemProfileProto::CHANNEL_DEV;
  54     case chrome::VersionInfo::CHANNEL_BETA:
  55       return SystemProfileProto::CHANNEL_BETA;
  56     case chrome::VersionInfo::CHANNEL_STABLE:
  57       return SystemProfileProto::CHANNEL_STABLE;
  58     default:
  59       NOTREACHED();
  60       return SystemProfileProto::CHANNEL_UNKNOWN;
  61   }
  62 }
  63
  64 }  // namespace
  65
  66 MetricsLogBase::MetricsLogBase(const std::string& client_id, int session_id,
  67                                const std::string& version_string)
  68     : num_events_(0),
  69       locked_(false) {
  70   if (IsTestingID(client_id))
  71     uma_proto_.set_client_id(0);
  72   else
  73     uma_proto_.set_client_id(Hash(client_id));
  74
  75   uma_proto_.set_session_id(session_id);
  76   uma_proto_.mutable_system_profile()->set_build_timestamp(GetBuildTime());
  77   uma_proto_.mutable_system_profile()->set_app_version(version_string);
  78   uma_proto_.mutable_system_profile()->set_channel(
  79       AsProtobufChannel(chrome::VersionInfo::GetChannel()));
  80 }
  81
  82 MetricsLogBase::~MetricsLogBase() {}
  83
  84 // static
  85 uint64 MetricsLogBase::Hash(const std::string& value) {
  86   // Create an MD5 hash of the given |value|, represented as a byte buffer
  87   // encoded as an std::string.
  88   base::MD5Context context;
  89   base::MD5Init(&context);
  90   base::MD5Update(&context, value);
  91
  92   base::MD5Digest digest;
  93   base::MD5Final(&digest, &context);
  94
  95   std::string hash_str(reinterpret_cast<char*>(digest.a), arraysize(digest.a));
  96   uint64 hash = HashToUInt64(hash_str);
  97
  98   // The following log is VERY helpful when folks add some named histogram into
  99   // the code, but forgot to update the descriptive list of histograms.  When
 100   // that happens, all we get to see (server side) is a hash of the histogram
 101   // name.  We can then use this logging to find out what histogram name was
 102   // being hashed to a given MD5 value by just running the version of Chromium
 103   // in question with --enable-logging.
 104   DVLOG(1) << "Metrics: Hash numeric [" << value << "]=[" << hash << "]";
 105
 106   return hash;
 107 }
 108
 109 // static
 110 int64 MetricsLogBase::GetBuildTime() {
 111   static int64 integral_build_time = 0;
 112   if (!integral_build_time) {
 113     Time time;
 114     const char* kDateTime = __DATE__ " " __TIME__ " GMT";
 115     bool result = Time::FromString(kDateTime, &time);
 116     DCHECK(result);
 117     integral_build_time = static_cast<int64>(time.ToTimeT());
 118   }
 119   return integral_build_time;
 120 }
 121
 122 // static
 123 int64 MetricsLogBase::GetCurrentTime() {
 124   return (base::TimeTicks::Now() - base::TimeTicks()).InSeconds();
 125 }
 126
 127 void MetricsLogBase::CloseLog() {
 128   DCHECK(!locked_);
 129   locked_ = true;
 130 }
 131
 132 void MetricsLogBase::GetEncodedLog(std::string* encoded_log) {
 133   DCHECK(locked_);
 134   uma_proto_.SerializeToString(encoded_log);
 135 }
 136
 137 void MetricsLogBase::RecordUserAction(const char* key) {
 138   DCHECK(!locked_);
 139
 140   UserActionEventProto* user_action = uma_proto_.add_user_action_event();
 141   user_action->set_name_hash(Hash(key));
 142   user_action->set_time(GetCurrentTime());
 143
 144   ++num_events_;
 145 }
 146
 147 void MetricsLogBase::RecordHistogramDelta(const std::string& histogram_name,
 148                                           const HistogramSamples& snapshot) {
 149   DCHECK(!locked_);
 150   DCHECK_NE(0, snapshot.TotalCount());
 151
 152   // We will ignore the MAX_INT/infinite value in the last element of range[].
 153
 154   HistogramEventProto* histogram_proto = uma_proto_.add_histogram_event();
 155   histogram_proto->set_name_hash(Hash(histogram_name));
 156   histogram_proto->set_sum(snapshot.sum());
 157
 158   for (scoped_ptr<SampleCountIterator> it = snapshot.Iterator();
 159        !it->Done();
 160        it->Next()) {
 161     HistogramBase::Sample min;
 162     HistogramBase::Sample max;
 163     HistogramBase::Count count;
 164     it->Get(&min, &max, &count);
 165     HistogramEventProto::Bucket* bucket = histogram_proto->add_bucket();
 166     bucket->set_min(min);
 167     bucket->set_max(max);
 168     bucket->set_count(count);
 169   }
 170
 171   // Omit fields to save space (see rules in histogram_event.proto comments).
 172   for (int i = 0; i < histogram_proto->bucket_size(); ++i) {
 173     HistogramEventProto::Bucket* bucket = histogram_proto->mutable_bucket(i);
 174     if (i + 1 < histogram_proto->bucket_size() &&
 175         bucket->max() == histogram_proto->bucket(i + 1).min()) {
 176       bucket->clear_max();
 177     } else if (bucket->max() == bucket->min() + 1) {
 178       bucket->clear_min();
 179     }
 180   }
 181 }